|If it's possible to run a network cable from your existing router to your "man cave" then I would do that.|
The maximum segment length for a Cat5/5e/6 cable is 100 metres. If the distance between router and man cave is less than that, you're good to go.
You can have a cable made any length you want keeping in mind the length limitation.
If you can do a wired solution, I would recommend doing so as wireless is not as good for gaming as wired. For a guide on how to connect a second router simply click on my name above in this response and read my “how-to” guide titled, “Add a second Router to your LAN”
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.